Hydraulic governor apparatus



7, 1956 J. s. DALE HYDRAULIC GOVERNOR APPARATUS 2' Sheets-Sheet 1 Filed June 9, 1952 IN V EN TOR. %Aep Q42, BY

ATTORNEYS.

Aug. 7, 1956 J. s. DALE 2,757,922

HYDRAULIC GOVERNOR APPARATUS Filed June 9, 1952 2 Sheets-Sheet 2 INVENTOR:

United States Patent HYDRAULIC GOVERNOR APPARATUS Joseph S. Dale, Rockford, Ill., assignor to Bale Hydraulic Controls, Inc., Rockford, 111., a corporation of Illinois Application June 9, 1952, Serial No. 292,400

9 Claims. (Cl. 264-3) This invention relates to hydraulic governor apparatus; in particular, it relates to an improved hydraulic governor adapted for use in applications calling for automatic increase in the speed of the controlled engine as a function of increasing load.

The present application is a continuation-in-part of my copending application Serial No. 139,076, filed January 17, 1950, entitled Hydraulic Speed Governor, now U. S. Patent No. 2,667,345.

Generally speaking, the object sought by prior-art engine governors has been constancy of engine speed. The engine being controlled might during its operation be subjected to widely varying loads. The function of the governor, whether it be hydraulic or mechanical, has been to regulate the fuel supply under varying load conditions to maintain the engine speed constant.

In some cases, prior-art governors have been provided with mechanism operative to cause the controlled engine to slow down slightly as the load on it is increased. Such operation is commonly known in the governor art as speed droop. Obviously, the effect of speed droop is intentionally to reduce the effectiveness of the governor action, since the extreme case of speed droop would be one in which no governor at all were being used and in which the fuel supply were constant.

The object of the present invention is to provide a stable governor operative to raise the engine speed as the load increases, and to reduce the engine speed with reduction in load. Thus, the function of the present invention difiers sharply from the traditional function of engine governors.

My invention finds many practical applications in fields where the speed of a prime mover must vary during operation. Outstanding among its applications is the diesel-electric locomotive. In such locomotives, diesel engines are employed to drive electric generators, which, in turn, supply electric current for motors which are geared to the driving wheels. Each locomotive is normally provided with several diesel engines, and the locomotives are regularly operated in groups of from two to four units, under the common control of a single engineer.

In prior-art practice, speed changes have been accomplished by simultaneously varying the speed settings of all the governors in a given locomotive or group of locomotives. Such adjustment has caused the fuel supply to the engines to be automatically regulated for the desired speed, and the field current supplied to the generators has been automatically regulated to maintain the locomotive at the desired speed, the fuel supply to the diesel engines being correspondingly regulated with variations in load.

This complicated arrangement has been expensive to install, particularly where several locomotives were to be operated together under unified control.

Under the system with whieh my invention is adapted for use, the manual speed control operated by the engineer merely adjusts the field current supplied to the electric generators. (Field current is ordinarily supplied from a suitable auxiliary energy source, such as storage batteries.)

As the field current is, for example, increased, the load on the diesel engines is increased. By the novel action of my present invention, the speed setting of the diesel engines is simultaneously increased by a controlled amount. The engine speed goes up quickly but stably to the new, higher value, and the electrical energy supplied to the motors is accordingly increased. The locomotive, as a result, of course runs faster.

Similarly, when thefield current is reduced by the engineer, the diesel-engine speed is automatically reduced,

and the locomotive slows down responsively to the lesser supply of electrical energy to the motors.

Thus, by means of the novel governor which comprises the present invention, the complicated locomotivecontrol systems now in use may be replaced by a simple field rheostat with which the locomotive engineer can merely adjust at will the field current supplied to the generators of the locomotive units under his control. Thus, in my system, complete control of diesel-engine speed between idling speed of, perhaps, 300 R. P. M. to a top operating speed of perhaps 900 R. P. M. is accomplished solely by variation .of the load on the engines.

The principal object of my present invention is to provide a hydraulic speed governor capable of accomplishing such a result.

More specifically, it is an object of the present invention to provide a hydraulic speed governor wherein the speed setting is automatically. increased when the load on the engine is increased, and wherein such increase in speed setting is accompanied by a strong but transient force applied to the pilot valve of the governor for bringing the engine to its new speed gradually and without any tendency toward instability.

In addition .to its usefulness in controlling locomotive engines, the present invention has application in all of the many fields in which prime movers are used to actuate variable-speed load devices.

Other objects and advantages of the present invention will be evident from the detailed description of the invention which follows.

I have in the appended drawing shown my invention as embodied in a hydraulic governor similar in many respects to that described and claimed in my said copending application Serial No. 139,076, now U. S. Patent No. 2,667,345. In the present drawing, I have shown such of the structural features of the governor as are pertinent to the present invention or :necessary to a full understanding thereof. It should be borne in mind, however, that the present invention is not limited to use with the particular hydraulic governor shown in the drawing but maybe incorporated in any hydraulic governor of the type havinga-pilot valve, a speeder spring, and fiyweights.

In the drawing, Figure-1 is a front elevation view showing the general outlines of the casing of a hydraulic governor embodying my invention; Fig. 2 is a plan View of the governorof Fig. l, with the top covering removed; Fig. 3 is a fragmentary sectional view, partially diagrammatic, showing the internal passageways and ports which cooperate with.the pilot valve and servo cylinder; Fig. 4 is a fragmentary view, partially in section, showing the structural detail of the apparatus by which changes in speed setting are made responsively to changes in load; and Fig. 5 is a fragmentary view, partially in section, bringing out the structural details of a portion ofthe compensation apparatus which forms an important part of the present invention. p

The governor shownin the drawing is enclosed-within a cast housing .20, preferably formed of aluminum. The casing 20 has a 'top plate 20a and a bottom plate 20b,

respectively bolted to the main casing 20 to provide a fully enclosed, liquid-tight housing for the governor apparatus.

The interior of housing 20, in addition to carrying the operative elements of the governor, functions as a sump or reservoir, at atmospheric pressure, for the light oil or other liquid employed as hydraulic fluid. If desired, a suitable cap aperture 29 may be provided in the top plate 20a as a convenient means of replenishing the hydraulic fluid when necessary. To insure that the gas pressure within the casing is held at atmospheric value, an air vent may, if desired, be provided in cap 29.

In the normal operation of my governor, the oil level within the casing should be' slightly more than half way up the side thereof. I have provided a transparent window 25, which may be formed of glass or plastic, in the front of casing 20 to provide a convenient means of observing the oil level.

Connection with the shaft of the controlled engine may be made through drive shaft 21, which projects downward from the bottom of casing 20. As is conventional in governor practice, drive shaft 21 may be linked in any suitable manner with the propeller shaft of the engine being controlled. Control of the engine by the governor is accomplished via output or control shaft 22, which is horizontally oriented and mounted in suitable hearings in the sides of casing 20; for convenience in installation with a variety of engines, shaft 22 may be extended beyond the casing at both ends, as shown. Shaft 22 is secured against axial movement, its rotation being governed by the control action of the governor. When the governor is installed on an engine, shaft 22 will normally be connected by suitable linkage to the fuel control of the engine, as shown, for example, in Fig. of said copending application Serial No. 139,076, now Patent No. 2,667,345.

On the upper portion of the face of casing I have provided an instrument panel which carries the manual controls with which my governor is adjusted and regulated. Shut down of the engine may be accomplished by means of a manual control 27, the operation of which is fully described in the aforesaid copending application; since it forms no part of the present invention, I shall not in this specification describe the shut-down mechanism in detail.

The panel 30 also carries a manual control knob 26 which may be used as a manual speed control. The function of manual speed control 26 differs in the present invention, however, from its function in conventional governors. Conventional governors are designed to hold the controlled engine at a constant speed determined by the setting of the manual speed control. In the present invention, the engine speed will be controlled, within a relatively wide range, by the governor itself, acting responsively to the load on the engine. Therefore, in the present invention, the function of manual control 26 is to fix the range of speeds within which the engine will operate, rather than to fix a constant operating speed.

Another Window 24 in the front face of casing 20 may be provided with a scale and used as a load indicator, in cooperation with a suitable marked reference point on link 82. Link 82 is the mechanical coupling between output shaft 22 and the hydraulic servo piston 78, and its vertical position provides a measure of the supply of fuel to the controlled engine at any given time.

As may be seen from Fig. 3, bottom plate 20b carries on its upper surface a central casting 200, which serves to support most of the governor apparatus and which contains cylindrical bores for the pilot valve, the servo piston, the compensation piston, and other important parts of the apparatus.

A central bore extends vertically through the entire casting 20c. Carried within bore 35 is a gear member 38 which, at its lower axial extremity, is keyed to shaft 21. Gear 38 forms part of a gear pump for supplying hydraulic liquid under pressure to the pilot valve.

The details of the gear pump which comprises gear 38 are fully disclosed in the aforesaid copending application of which this specification is a continuation in part. Since the gear pump forms no part of the present invention, it will not be described in detail in this specification. It will sufiice to state that whenever shaft 21 is being turned by the controlled engine, the gear pump 38 provides hydraulic liquid under pressure at port 49a, which commuicates with the central chamber of the pilot valve, as is hereinafter more fully described.

Shaft 21 is supported within base plate 20b by means of bearings 36, and a suitable seal around shaft 21 is provided by stuffing box 37.

The pilot valve comprises a spool valve member 54 and a valve sleeve 46. Sleeve 46 is shrink-fitted or otherwise tightly secured within bore 35, and its interior surface is machined with the greatest care and accuracy. The valve member 54, throughout most of its length, is substantially smaller in diameter than the inner diameter of sleeve 46, and it is provided with a plurality of control lands, numbered 54a, 54b, 54c, and 54d.

Rotation during operation may be imparted to valve spool 54 by means of spring coupling 57, providing a limited torque transfer between gear member 38 and the lower end of valve member 54.

A gear 58 is provided with a carefully machined hub member which is fitted into a cooperating bearing machined into the upper end of sleeve 46. Gear 58 is keyed to a coaxially disposed cup member 59 which serves as support for the flyweight mechanism. Valve member 54 extends upward through suitable apertures in the centers of members 58 and 59, terminating in anti-friction bearing structure 60.

Gear member 58 meshes with a gear 61 supported in a stationary bearing carried by casting member 20c and driven by shaft 62 which extends vertically to a gear (not shown) which meshes with gear 38. Thus, on rotation of shaft 21, cup member 59 is caused to rotate. Cup 59 has a raised rim 59a around its periphery, the function of which is primarily to keep sump oil from getting into contact with and thus affecting the operation of the flyweights. The normal oil level in the casing is lower than cup member 59, but the rim 5951 provides added insurance against the oils interfering with the free movement of the flyweights.

Cup member 59 is provided with a pair of parallel cross walls 59b which carry the bearings which support the flyweights (not shown). Each of the flyweights is provided with a laterally extending finger 64a, the inner end of which presses on the under side of anti-friction bearing structure 60. Thus, when the flyweights move outward due to centrifugal force of rotation, the fingers 64a press on the under side of bearing structure 60 and thus raise valve member 54. Conversely, when the fiy weights slow down, fingers 64a press on thrust bearing 60 with less force and thus permit valve member 54 to move downward under the force of speeder spring 65.

Since the structural details of the flyweights do not form a part of the present invention, I have not shown in the present drawing the details thereof, but such details are fully disclosed in Fig. 13 of the aforesaid copending application, now Patent No. 2,667,345.

Thrust bearing 60 is modified on its upper surface to provide a spring seat for the lower end of speeder spring 65. The upper end of speeder spring 65 is seated against an upper spring seat 68, which bears against sleeve 67.

Sleeve 67 is slidably carried within a bracket 66 extending outward in a horizontal plane from the front face of casing 20. Bracket 66 carries at its inner end a hollow cylindrical portion best seen in Fig. 2. The inner surface of the cylindrical portion of bracket 66 is accurately machined for smoothness and constant curvature.

A plunger 69 is slidably carried within sleeve 67, plunger 69 being provided on its upper surface with a roller 'or' cam follower 69u, carried on ianaxle 69i; suitably journaled in a transverse Jbore in plunger 69.

The relativepositio'n :of iplunger 69 "and sleeve 67 is governed by'the position of :a .sector pinion :70 relative to rack 72. Pinion 270:;is :carried onashaft 25b "which is .connected by a :suitable flexible icoup'ling :to knob 26 on panel 30. Rack .72 'isRbOltedttoLtheiside of ;sleeve .67 and is carried slidably inia vertiealslot 731in (bracket '66. By thus riding in .slot 73, :rack 72 secures :sleeve :67 against rotation in brackett66, whilerallowing'itrfull freedom to move in the axial direction.

By manual adjustment of:lmob .226, :the relative ,position of plunger 69 and :sleeve J67 may he set to the desired value. Since, as will be hereinafter more fully described, plunger 69 .is limited in .its 'upward movement, it will be understood from the foregoing that-adjustment of the relative position of plunger 69 and sleeve .67 permits variation, within 'wide limits, of the compression of spring 65 and-hencethe torceexerted-by-it.

The lands 54a, 54b, :and 540, together with the increased-diameter :portion of spool :54 .lying below land 54c, define a plurality -.of valve chambers within :sleeve 46. Ports 47a, 49a, and Sic-communicate respectively with those chambers; those ports :are -all of relatively large size, the size being non-critical. As heretofore mentioned, port 49a communicates through an appropriate passage (not shown) with the gearipumpheretofore mentioned, and via-port49a,a supplyofthydraulic liquid under pressure is continuously fed into the chamber defined between lands .5412 and 54a. Ports 47a and 51a communicate directly with sump via ,passagesSZ and v53 respectively.

Ports 48a and 59a .are valve-control ports which cooperate with lands ,5.4b,and.54c respectively. Ports 48a and 50a are carefully .drilled to .a diameter very .slightly greater-a few .thousandths ofan -inch-than the .thickness of lands 54b and.54c, itheflands being of equal size. Thus, whenpilot valve .mernber 541s in'its normal position, as shown in Big. 3, the lands ,S lband 540, with the ports 48a and 50a, fformaibalanced by-pass system carrying the hydraulic 'liquidffrom rthegearpump to sump in equal volumes, thus maintaining equal pressures in the annular recesses 48 and 5.0.

Annular recess 48'is connected by a passage 76 to the upper end of a cylinder 74, and annular chamber 50 is connected by a passage 75 with .atlower point in cylinder 74, as maybe seen l'from Fig.3, is'bored in central casting 20c, and contains a valve member 87 provided with aprincipal valve portion "87a generally cylindrical in shape but provided .with two flat cut away portions, one of which'beg'ins intermediate'the ends of the cylinder and extends to the top while the other'beginson the 0pposite side of the cylinder near "the upper end and extends to 'the bottom. Valvemember 87atis oriented on the stem of'valve meniber87'in such ap'osiitionthat'the fiat portionextending to the top of "member 87 provides communication between passage76 and passage 84, while the other flat portion provides 'cornmunicationbetween passage 75'andpassage85.

At the 'lower end "of element 87 a cylindrical land 87b -fitssnugly within cylinder74, thus "normally blocking off transverse bore85 from vent 74a, which leads to 'sump.

Transverse bore 84 connects "cylinder 7% with the upper end of servo cylinder 77, "while passage 85 connects the lower end =of 'cylinder 74 with the l'owe'r end of servocylinder 7'7.

Servo cylinder 77 is provided with a piston 7 8carried on a piston rod 79. The lower end fof piston :rod 579 is received within arrece'ss "80, which carries a ventrpassage -80a connecting to :sump. 1A packing element "86 provides a seal :for .piston rod 79.

tSp'ool valve member .87 is :suitably (connected tbyrmeans of coupling .88 to mechanical linkage actuated by the manual shut-:down :contrdl 27. when "the valve member t6 87 :is in the 5 position 'shown1in Fig. .3, ':the governorwill operate normally. When manual control 27 .is moved to the ofF position, valve member 87 is raised, with the result that passage 84 :is connected to passage instead of'to passage 76, whileatthe same timepassage 85 is connected .to sump.

Piston rod .79 of :servo piston 7-8 .passes through a bearing drilled in casting 20 and is attachedby 'apivot coupling 81 to link 82. Link '82, in turn, is joined by means of a pivoted coupling :to crank member :91 which is rigidly keyed to control shaft 22. Thus, .shiftsrin the vertical position of servo piston 78 :are reflected as rotational movements of shaft 22.

I shall now describe the structure by which compensation is introduced in'my invention to stabilize its operati-on and to avoid hunting.

A vertical bore 92 in casting 20c functions as compensation cylinder. It contains a central bore at the top which receives a vertical :rod .93 extending entirely through bore 92 and seating in -a recess 94 in bottom plate 20b. Recess 94 isprovi'ded with-a sump'vent 9411. A packing ring 95, fitted into ithe lowesttportion of bore 92, holds rod '93 in alignment, permitting it :free axial movement without binding. Atiits upper "end rod 93 :is pivoted to a link "'96 which extends upward to a point near the top of the casing, at whichit-is .pivoted on a pin 151 secured by lock-nut 152 within -a slot 153 in lever 154.

Lever 154 is pivoted at \one end Ito a :bracket 156 rigidly secured to the easing. iL-ever 154, in addition to the horizontal slot 153, .is.also provided with .a vertical slot which receives the end of link 96. Ihe width of slot 155 is slightly greater than the thickness of link 96, so that link 96 will pivot freely onpin '151 even after the pin has :been locked in a particular posi'tion in slot 153 by the tightening :of nut 152. The free end of lever 154 carriesia spring seat 157; a tension spring 158 is carried between ispringseat 1'57 and a pin 159 which is rigidly affixed to the side of the casing.

The lower edge of lever 154 is provided with a shaped cam-follower face (:see Fig. 5).

Output shaft 22 passes a 'short distance below :lever 154, and a cam 1'61 is rigidly keyed to shaft 22 'a't'the position 'whereat the upper face of cam 1'61 will bear on the cam-follower surface :of lever 1 54. The team 1 61 and the follower surface of lever 154 are shaped so as to cause lever 154 to rise quite rapidly in response to rotation of shaft 22; that is, a slight rotation 10f shaft 22 will produce a rather substantial shift in'the position of lever 154 and of linkl96.

Rod '93 is provided, within cylinder :92, with an upper spring seat 101 and a lower spring seat E102. 'Iihese spring seats are machined to fit rather loosely within cylinder "92. Floating -on rod :93 between \the spring seats is a plunger 103 which is machined for a slidable fit within the cylinder. It carries :on both its :upper and lower faces annularrflanges which-serve as spring seats. A :coil spring 104 is seated :on ithe upper face :of plunger 103, where it presses upward against ispring (seat 101. A second coil spring 10.5 is seated around 'rod *93 between lthe lower face of plunger 1'103Land spring seat 102.

A transverse bore 106 "connects :the uppermost part of -the enlarged-diameter portion of :sleeve -46 with ithe lower portion of cylinder 92; .a transverse bore 107 conmeets the lowermost portion :of the =-enlarged-diameter part 'of sleeve 46 ato the upper portion 20f cylinder :92. IA branch bore 106a connects bore .106 to ;a needle valve 108 communicating with sump. Similarly, a needle valve .109 is connected 'by a branch bore 107a to bore 107, valve 109 exhausting also to :sump.

The needle valves 108 and 109 are made manually adjustable .in any suitable manner, such as that disclosed in detail in my aforesaid colpending application, .now Patent :No. 2,667,345.

Land :54d on .spoo'l valve meinbers54pis carriedriwithin the aforesaid enlarged-diameter portion of sleeve 46 and is machined for a sliding fit therewith. Sump port 55, which passes through the wall of sleeve 46 and cooperates with land 54d, is drilled to a diameter equal, within approximately one-thousandth of an inch, to the thickness of land 54d. When spool valve member 54 is in the normal position shown in Fig. 3, port 55 is entirely covered by land 54d.

Referring now primarily to Fig. 4, I shall describe the apparatus by which the deformation of speeder spring 65 is controlled by the position of shaft 22.

As may be seen from Figs. 2 and 4, shaft 22 passes through the governor casing adjacent and approximately on a level with the midline of bracket 66. Directly opposite bracket 66, shaft 22 is provided with a lever 171 keyed to the shaft for rotation therewith. The upper end of lever 171 is pivoted to a bifurcated link 172 which extends across the casing directly over plunger 69 and roller 69a. At its far end, link 172 carries a downward extension, the lower end of which is pivoted to a lever 173 which, in turn, has its lower end pivoted on a pin 174 carried by bracket 66. The pivot which joins lever 173 and link 172 is disposed intermediate the ends of lever 173, and the free end of lever 173 is pivoted to a bifurcated link 175. The other end of link 175 is pivoted to a wedge-shaped cam member 176, the plane upper surface of which slides in a track machined in boss 177, which is carried on or formed integrally with the under side of cover plate a.

The lower surface of cam member 176 forms a curved cam face which bears upon roller 69a.

As may be readily seen from Fig. 4, rotation of shaft 22 causes cam member 176 to slide forward or backward along boss 177 and thereby lowers or raises plunger 69. Changes in the position of plunger 69 are of course accompanied by changes in the deformation of spring 65 and hence of the downward force exerted by the spring on pilot valve member 54.

Operation In describing the operation of my invention, I shall assume that my governor has been installed on a prime mover, such as a diesel engine, and that the diesel engine is coupled to a variable load, such as an electric generator whose field current may be manually varied. In such an installation, which is typical of that encountered in, for example, a diesel-electric locomotive, the prime mover will normally be started when the locomotive is stationary and when, therefore, the load is minimum. In other words, when the engine is first started, it will be operating under idling conditions.

At the outset, manual speed control 26 may be adjusted to set the idling speed at the desired level. With a typical large diesel engine, that may be about 300 R. P. M.

Under those conditions, the speeder spring 65 will force pilot valve member 54 downward, cutting off the flow of hydraulic fluid through port 48a and increasing the flow thereof through port 50a. At the same time, the passage to sump port 47a from transverse bore 76 will be increased in size. That action will cause hydraulic fluid to flow into cylinder 77 below piston 78 and force link 82 to rise, causing shaft 22 to rotate in the direction which, in Fig. 4, is counterclockwise. The engine will increase in speed as a result of the increased fuel supply thus provided, and the centrifugal force developed by the flyweights will increase accordingly. When the point is reached at which the upward force exerted by flyweight fingers 64a becomes suflicient to balance the downward force of speeder spring 65, the pilot valve 54 will return to its normal position and piston 78 will come to rest. During the increase of speed incidental to reaching normal idling speed, the position of plunger 69 will remain unchanged, since during that portion of the movement of control shaft 22, the sur- 8 face of cam 176 which is in contact with roller 69a is flat and substantially horizontal.

After the engine is running smoothly at idling speed, suppose the engineer desires to start the locomotive. He will thereupon adjust his field rheostat and start supplying current to the generator field windings. That will require increased torque for rotation of the armature, so the prime mover will begin to slow down. At the first trace of reduced speed, however, speeder spring 65 will again force the pilot valve downward and cause further rotation of shaft 22 in the direction of increased fuel supply. That will, at the same time, pull cam 176 further to the left, as viewed in Fig. 4, and thus increase the compression of spring 65.

But for the operation of my invention, the action just described would be inherently unstable, since an increase in the compression of spring 65 would immediately be followed by a further lowering of the pilot valve, which, in turn, would produce additional movement of the servo piston, followed by a still further increase in the compression of spring 65. This cycle would continue until the servo piston should have moved the maximum possible distance in the direction giving increased fuel supply. In other words, the cycle of events would continue until the controlled engine were running wide open.

My invention prevents such a series of events from taking place, however; at the instant rotation of shaft 22 begins to increase the compression of spring 65, earn 161, rotating with shaft 22, raises link 96 sharply. This movement raises spring seat 102, compresses spring 105, and creates, temporarily, a strong hydraulic pressure below land 54d, opposing and preventing the downward movement of the pilot valve which would normally result from the increasing compression of spring 65.

The transient hydraulic pressure thus produced will gradually drop off as liquid leaks through needle valve 109. During that interval, however, the engine speed will increase as a result of the added fuel provided by the initial movement of the servo piston, and as the engine speed increases, the upward force exerted on the pilot valve by the flyweight fingers 64a increases until it becomes sufficiently great to balance the added force of spring 65. The time constant of the compensation apparatus should be adjusted, by appropriate setting of needle valve 109, to keep the transient compensation pressure below land 54d high enough to prevent further downward movement of the pilot valve until the engine has time to increase speed and thus increase the force exerted on the pilot valve by the flyweights. While the governor operation is entirely stable if this time constant is longer than necessary, a long time constant does necessarily reduce somewhat the speed with which the controlled engine will adjust itself to new load and speed conditions. Therefore, it is desirable that valve 109 be adjusted to provide a time lag approximately equal to the time required for the engine to reach the new speed called for by the initial movement of the servo piston.

When the load is reduced, the engine speed drops accordingly, the cycle of events being similar. That is, a reduction in load causes the engine momentarily to speed up, with the result that pilot valve 54 is momentarily raised by flyweight fingers 64a. This causes the flow of fluid through port 50a to be cut off and at the same time increases the flow through port 48a. That action leads to increased flow of hydraulic liquid into cylinder 77 above servo piston 78, forcing piston 78 downward.

The resulting rotation of shaft 22 reduces the supply of fuel to the engine and at the same time causes cam 176 to move on roller 69a, reducing the compression of spring 65. As before, however, disproportionate speed reduction is prevented by the action of the compensation cylinder, since the rotation of shaft 22 lowers link 96, compressing spring 104 and causing a transient renames hydraulic pressure above land 54d, opposing and temporarily preventing the upward movement 'of pilot valve 54 which would normally result from-the reduced compression of spring 65.

The hydraulic pressure from the compensation cylinder gradually drops off, the rate of pressure drop being controlled in this case by the adjustment of valve 108. As with the case of increased load, the compensation pressure holds the pilot valve until the reduced speed of the engine sufficiently reduces the centrifugal force of the fiyweights to balance the reduced force exerted by speeder spring 65.

As explained and claimedin my aforementioned earlier patent application, needle-valves 108 and 109 operate entirely independent of one another, since during any period in which one'of the valves 'isfunctioning the other valve is effectively "by-passed to sump by port 55, the appropriate side of which is uncovered by any movement of pilot valve 54. This structure thus permits entirely independent compensation adjustment on both acceleration and deceleration.

The particular. compensation apparatus shown herein thus contributes greately to the smooth operation of my governor and to optimum reaction time on both acceleration and deceleration. The compensation apparatus is claimed per se in said earlier application, now Patent No. 2,667,345, and is accordingly not thus claimed herein.

While I have herein described in considerable detail a particular embodiment of my invention, that detailed description is intended to be exemplary only. It is my desire that the scope of my invention be determined primarily with reference to the appended claims.

I claim:

1. In a hydraulic governor structure adapted for use with a prime mover having a variable load for correcting the prime mover speed in accordance with changes in the load thereof, the combination with a responsive member movable in direction and extent in accordance with the direction and magnitude of a change in the operating speed of a prime mover effected by a change in the load thereof, a movable output member, the position thereof determining the operating speed of a prime mover, and hydraulic circuit means interconnecting said responsive and output members for shifting the position of the latter in proportion to a change in position of the former to correct the speed change of the prime mover and thereby maintain it at a preselected operating speed, means for over-correcting the speed of the prime mover in the direction of correction thereof comprising a cam follower coupled with said responsive member for applying a force thereto tending to move it in one direction, a cam for said cam follower, and means coupling said cam and output member to shift the cam upon movement of the output member, said cam being contoured to selectively increase and decrease the force applied by said cam follower to increase the magnitude of the movement of said responsive member resulting from a change in the load of the prime mover.

2. In the combination of claim 1, compensating means in said hydraulic circuit means for applying a transient force to said responsive member in opposition to the direction of movement thereof for limiting and stabilizing the speed correction provided by said responsive and output members.

3. In a hydraulic governor structure adapted for use with a prime mover having a variable load for correcting the prime mover speed in accordance with changes in the load thereof, the combination with a responsive member movable in direction and extent in accordance with the direction and magnitude of a change in the operating speed of a prime mover effected by a change in the load thereof, a movable output member, the position thereof determining the operating speed of a prime mover, and hydraulic circuit means interconnecting said responsive and output members for shifting the position of the latter in proportion we change in positionofthe former to correct the speed change of the prime mover and thereby maintain it at a preselected operating speed, meansfor over-correcting the speed of the prime mover in the direction of correction thereof comprising cam means, means coupling said cam means and responsive member for applying a force thereto tending to move it in one direction and means coupling said cam means and output member for selectively increasing and decreasing the force applied by said cam means upon movement of said output member to increase the magnitude of the movement of said responsive member resulting from a change in the load of the prime mover.

4. In the combination of claim 3, anti-hunt means for limiting and stabilizing the speed correction provided by said responsive and output members.

5. In a hydraulic governor having a speeder spring, fly weights for controlling the .compression of the speeder spring, a pilot valve controlled by the speeder spring, and a servo piston controlled by the pilot valve and being equipped with an output member adapted to be connected with the fuel supply control of a prime mover for adjusting the same, said governor being selectively operative to increase or decrease the prime mover fuel supply respectively when increasing or decreasing loads are applied to the prime mover to stabilize the operating speed thereof at a substantially constant level, means for over-correcting the speed of the prime mover in the direction of correction thereof comprising cam means, means coupling said cam means and speeder spring for applying a compressive force thereto, and means coupling said cam means and output member for selectively increasing and decreasing the force applied to said speeder spring by said cam means upon movement of said output member to increase the magnitude of the control response of said speeder spring and thereby over-correct the speed of a prime mover in the direction of correction thereof.

6. The structure of claim 5 in which said cam means comprises a plunger providing a seat for said speeder spring, and a cam coupled with said plunger.

7. An engine governor having a drive shaft adapted to be rotated by an engine, fly weights turned by rotation of the drive shaft, a pilot valve actuated by the fly weights, a speeder spring opposing the action of the fly weights on the pilot valve, said pilot valve, through said speeder spring, being responsive to a change in the operating speed of the drive shaft, an output member for controlling the speed of an engine and being responsive to said pilot valve, cam means, means coupling said cam means and speeder spring for applying a compressive force thereto, and means coupling said cam means and output member for moving said cam means to selectively increase and decrease the compressive force applied thereby to said speeder spring upon a change in condition of said output member, said cam means being operative to increase the magnitude of the response of said pilot valve, by changing the compressive force on said speeder spring, in accordance with the direction of response thereof so that the operating speed of an engine is over-corrected by said governor following a change in the operating speed thereof.

8. In a hydraulic governor providing a hydraulic circuit, a pilot valve movable to control the flow of fluid through said circuit, a control member responsive to said pilot valve and being adapted to control the operating speed of an engine, and a speeder spring providing a biasing force on said pilot valve in determining the position thereof, means for changing the biasing force of said speeder spring in accordance with the extent of response of said output member to over-correct the operating speed of an engine following a change in the speed thereof so as to stabilize the engine speed at a higher value following a reduction in the operating speed thereof and to stabilize it at a lower value following an increase in the operating speed thereof, said means comprising a cam for applying a compressive force to said speeder spring and linkage means coupled to said output member for shifting the cam upon movement of said output member to alter the biasing force of said speeder spring.

9. In a hydraulic governor providing a hydraulic circuit, a pilot valve movable to control the flow of fluid through said circuit, a control member responsive to movement of said pilot valve and being adapted to control the operating speed of an engine, and a Speeder spring providing a biasing force on said pilot valve in determining the position thereof, means for changing the biasing force of said speeder spring in accordance with the extent of response of said output member to overcorrect the operating speed of an engine following a change in the speed thereof so as to stabilize the engine speed at a higher value following a reduction in the operating speed thereof and to stabilize it at a lower value following an increase in the operating speed thereof, said means comprising a plunger having a seat engaged by said speeder spring, a cam follower carried by said plunger, a cam engageable with said cam follower and being shiftable to move the same for altering the compression of said speeder spring, and linkage coupling said cam with said output member whereby said cam is shifted upon a change in the position of said output member.

References Cited in the file of this patent UNITED STATES PATENTS 2,364,115 Whitehead Dec. 5, 1944 2,364,116 Whitehead Dec. 5, 1944 2,374,276 French Apr. 24, 1945 2,478,183 Drake Aug. 9, 1949 2,560,758 Burritt July 17, 1951 2,667,345 Dale Jan. 26, 1954 

